Liver Of Catfish Research Articles

Extraordinary mullet growth through direct injection of foreign DNA

The present study aims to produce a genetically modified grey mullet, Mugil cephalus , with accelerated growth through direct injection of foreign DNA isolated from the liver of shark ( Squalus acanthias L.) or African catfish ( Clarias gariepinus ) into muscles of fingerlings fish at the dose of 40 μg/fish. The results show a significant (P≤0.05) improvement in most of the growth performance and body composition parameters of genetically modified grey mullet fingerlings injected with shark DNA compared to both genetically modified grey mullet injected with catfish DNA and the control fish, while the results of feed conversion ratio (FCR) and protein efficiency ratio (PER) indicate that fish injected with shark DNA or catfish DNA had significant (P≤0.05) superiority compared to their control. The results of the random amplified polymorphic DNA (RAPD) fingerprinting show highly genetic polymorphic percentage among grey mullet that received foreign DNA and their control using different random primers. This may be due to some fragments of foreign DNA randomly integrated into grey mullet genome. Therefore, the result indicates a possible easy and rapid way for improving fish characteristics. Keywords: Grey mullet, growth, foreign DNA, genetically modified

Deltamethrin-induced oxidative stress and biochemical changes in tissues and blood of catfish (Clarias gariepinus): antioxidant defense and role of alpha-tocopherol

BackgroundThe pyrethroid class of insecticides, including deltamethrin, is being used as substitutes for organochlorines and organophosphates in pest-control programs because of their low environmental persistence and toxicity. This study was aimed to investigate the impact of commonly used pesticides (deltamethrin) on the blood and tissue oxidative stress level in catfish (Clarias gariepinus); in addition to the protective effect of α-tocopherol on deltamethrin induced oxidative stress.Catfish were divided into three groups, 1st control group include 20 fish divided into two tanks each one contain 10 fish, 2nd deltamethrin group, where Fish exposed to deltamethrin in a concentration (0.75 μg/l) and 3rd Vitamin E group, Fish exposed to deltamethrin and vitamin E at a dose of 12 μg/l for successive 4 days.Serum, liver, kidney and Gills were collected for biochemical assays. Tissue oxidative stress biomarkers malondialdhyde (MDA) and catalase activity in liver, kidney and gills tissues, serum liver enzymes (ALT and AST), serum albumin, total protein, urea and creatinine were analysed.ResultsOur results showed that 48 h. exposure to 0.75 μg/l deltamethrin significantly (p < 0.05) increased lipid peroxidation (MDA) in the liver, kidney and gills while catalase activity was significantly decreased in the same tissues. This accompanied by significant increase in serum ALT, AST activity, urea and creatinine and a marked decrease in serum albumin and total proteins.ConclusionsIt could be concluded that deltamethrin is highly toxic to catfish even in very low concentration (0.75 μg/l). Moreover the effect of deltamethrin was pronounced in the liver of catfish in comparison with kidneys and gills. Moreover fish antioxidants and oxidative stress could be used as biomarkers for aquatic pollution, thus helping in the diagnosis of pollution. Adminstration of 12 μg/l α-tocopherol restored the quantified tissue and serum parameters, so supplementation of α-tocopherol consider an effective way to counter the toxicity of deltamethrin in the catfish.

Fatty acid binding protein 10 in the orange-spotted grouper (Epinephelus coioides): Characterization and regulation under pH and temperature stress

We have isolated and characterized a fatty acid binding protein from the liver of the orange-spotted grouper (Epinephelus coioides). Amino acid sequence similarity of the Ec-FABP (E. coioides-FABP) was highest to FABP10s isolated from the livers of catfish, chicken, salamander and iguana. The open-reading frame of the Ec-FABP codes for a protein of 14.0kDa with a calculated isoelectric point of 8.5. We first expressed a FABP10 protein from orange-spotted grouper (E. coioides) in Pichia pastoris, and then characterized the antioxidative potential of our recombinant Ec-FABP by DCF fluorescence assay. RT-PCR assays showed that endogenous Ec-FABP mRNA is most strongly expressed in liver with the most abundance and intestine. Change in the groupers’ blood cells respiratory burst activity was examined during and after exposure to the pH and temperature stress using flow cytometry. Further analysis of Ec-FABP gene expression in liver tissue by quantitative real-time PCR demonstrated that Ec-FABP transcript levels increased when the fish were exposed to both pH and temperature stress, but the time when its mRNA expression level peaked differed under these stresses. Western blot analyses confirmed that the Ec-FABP protein was strongly expressed in the liver after exposure to the pH and temperature stress. These results suggest that Ec-FABP expression is stimulated by pH and temperature stress and that it may play important roles in general adaptive and antioxidant responses.

Residue of Cadmium and Mercury in Liver and Muscle of a Freshwater Catfish Heteropneustes fossilis (Bloch)

Toxic metals viz., cadmium and mercury in liver and muscle tissues of a freshwater catfish, H. fossilis were measured by graphic mode and atomic absorption spectrophotometer (AAS). Fish were exposed to fractions of 96h LC 50 value. Acute (1/5 th of 96h LC 50 ), subacute (1/10 th of 96h LC 50 ) and sublethal (1/15 th of 96h LC 50) concentrations for acute (96h), short (10-20 days) and long (30-60 days) terms. The accumulation of both the metals in liver and muscle was significant in respect of dose and duration. The cadmium residue was found to be higher in liver than muscle but mercury was more in muscle than liver. It was also observed that, the relationship between the body concentration of each heavy metal and its respective 96h LC 50 value was close and sequenced.

Proximate and Fatty Acid Composition of the Liver of Cultured Asian Redtail Catfish (Hemibagrus nemurus) and African Catfish (Clarias gariepinus)

Catfish species are popular fish group consumed in Malaysia. African catfish, Clarias gariepinus and Asian redtail catfish, Hemibagrus nemurus are two of these catfish species. Unfortunately, some parts of these fish are removed during processing. This includes the liver which contained considerable amount of extractable lipid with both monounsaturated and polyunsaturated fatty acids. The fish samples were purchased and transported in ice box to the laboratory. Liver was extracted and analyzed for crude protein, crude lipid, moisture, ash, carbohydrate contents and fatty acid composition. Results were compared between male and female C. gariepinus and H. nemurus. Liver of female H. nemurus contained the highest amount of ash, crude lipid and carbohydrate and the lowest amount of moisture. Male H. nemurus had the lowest amount of protein, ash and crude lipid content. Moisture was found to be the highest in male C. gariepinus. The main fatty acid content of Asian redtail catfish and African catfish liver were C12:0, C14:0, C15:0, C16:0, C16:1, C17:0, C18:0, C18:1n-9, C182n-6, C183n-3, C204n-6, C24:1, C205n-3, C225n-3, C226n-3. The most abundant fatty acids in both species were oleic acid (18:1n-9) and palmitic acid (16:0). In conclusion, this study showed that H. nemurus and C. gariepinus, are two valuable source of protein and polyunsaturated fatty acid.

Regulation of cytochrome P4501A by protein kinase C: the role of heat shock protein70

Carbofuran is a pesticide, which is used throughout the world as a nematicide and an acaricide. This pesticide integrates into living organisms through aquatic ecosystem. In earlier report, we had demonstrated that cytochrome P4501A was induced in cultured catfish hepatocytes in response to carbofuran, which might be responsible for the detoxification of this pesticide. As the underlying signaling mechanism associated with induction and regulation of cytochrome P4501A has not yet been well defined, we therefore in the present study have investigated to identify the regulatory network of cytochrome P4501A in catfish liver or cultured hepatocytes by targeting several key signaling molecules such as phosphatidyl inositol (PI) or protein kinase C (PKC), which are critical molecules for many important pathways. PKC and heat shock protein70 (HSP70) have been shown to be induced in response to carbofuran in catfish hepatocytes. Results also indicate that induction of CYP1A is modulated by HSP70 and PKC in fish hepatocytes. Thus our data shed light on the regulation of EROD activity, which has been used as a bio-monitoring tool for measuring aquatic pollution.

Selenium speciation in different organs of African catfish (Clarias gariepinus) enriched through a selenium-enriched garlic based diet

Speciation of Se in fish is needed to elucidate the metabolism of this element in living organisms in the marine environment. In this paper, selenium concentration and its species distribution in several organs and tissues (liver, gills, kidney, muscle and gastrointestinal tract) of African catfish fed with a selenium-enriched garlic based diet was studied. The intention of this paper is focused on both the investigation of selenium distribution in the soluble protein fraction and the detection of selenoaminoacids. Thus, two different procedures have been developed. In the first procedure, screening of selenium in proteins in the Tris-buffer soluble fraction of different tissues was carried out by size exclusion chromatography-inductively coupled plasma-mass spectrometry (SEC-ICP-MS) and by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) after sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) separation and electroblotting onto membranes. For the amino acid analysis, several sample treatments for Se-species extraction, based on enzymatic hydrolysis, were compared. The best results were obtained for incubation at controlled temperature. Application of several sample treatments in conjunction with different chromatographic techniques (reverse phase, anion exchange and ion exchange/size exclusion) was crucial to unambiguous Se-species identification. In Se-enriched African catfish a noticeable increase in the content of selenium in different organs was observed, except for the liver, where the Se level remained unaltered. The kidney was the Se-target organ in animals fed with enriched Se food. Selenomethionine (SeMet) was the main Se species identified in fillet extracts, whereas the presence of selenocysteine (SeCys) was detected in the liver and both SeMet and SeCys were present in the kidney.

Histological alterations in the testes and ovaries of the sharptooth catfish (Clarias gariepinus) from an urban nature reserve in South Africa

Fish from two urban impoundments known to be polluted will have a higher incidence of gonadal histological alterations compared to fish grom a laboratory-bred referende group. The aim of the study was to examine possible reproductive health effects in male and female Clarias gariepinus, based on a histological assessment, and to compare the results to a laboratory-bred reference group (RG). Previous studies have shown histological alterations in both the gills and livers of catfish inhabiting these systems; and water and sediment analyses indicated levels of selected endocrine disrupting chemicals and metals. A sample size of 81 male and 81 female C. gariepinus specimens were collected from both impoundments. Testis and ovary samples were processed using standard techniques and prepared for light microscopy analysis. Histological alterations were semi-quantitatively assessed, and the results were classified according to the severity of the histological response identified. An internal examination of fish from the MD and RVD revealed abnormal gonadal structure in a number of specimens. The histological assessment of the RG revealed normal testicular and ovarian tissue structure. However, primary histological alterations identified in the gonads of fish from MD and RVD included melano-macrophage centers, vacuolation of germ cells and interstitial tissue, the presence of testicular oocytes, and cholesterol granulomas in the ovaries. It is recommended that laboratory exposures, using environmentally relevant concentrations of detected contaminants, be done using C. gariepinus to establish cause and effect relationships.

Reparation of chlorpyrifos-induced impairment by thyroxine and vitamin C in fish

The organophosphate pesticide chlorpyrifos significantly decreased the specific activities of catalase (CAT) and lactate dehydrogenase (LDH) in brain, liver, gill and skeletal muscle of the freshwater catfish, Heteropneustes fossilis. It may be due to binding of the pesticide or its metabolite(s) with the enzyme molecules or affecting the synthesis and/or degradation of the enzymes. RNA and protein content also declined significantly in different tissues of the fish in response to chlorpyrifos, which may be due to alterations in turnover of macromolecules involved in protein synthesis. Administration of thyroxine (T4) and ascorbic acid (vitamin C) separately or conjointly to chlorpyrifos-exposed fish brought CAT, LDH, RNA and protein up to their control levels. The protective effect may be attributed to hormone, vitamin and pesticide interaction. Therefore, chlorpyrifos-induced impairment in antioxidative, anaerobic and protein synthesizing capacity can be repaired by ascorbic acid and T4 in fish.

Oxidative enzymes in tissues of the catfish (Clarias gariepinus) exposed to varying levels of cadmium

The activities of some oxidative enzymes (aldehyde oxidase, AO, EC 1.2.3.1; xanthine oxidase, XO, EC 1.17.3.2; sulphite oxidase, SO, EC 1.8.3.1; and monoamine oxidase, MO, EC 1.4.3.4) were investigated in the liver, gill, kidney, brain and muscle of a variety of African catfish (Clarias gariepinus) after 7 and 21 days of exposure to 0.1, 0.2 and 0.4 ppm cadmium (Cd) in ambient water. MO, SO and AO activities were significantly (p < 0.05) decreased in a dose-dependent manner in the liver, kidney and gill in the 7-day Cd-exposed fish when compared to control. Conversely, brain MO, AO and SO activities were significantly (p < 0.05) elevated in a dose-dependent manner in the same fishes relative to control. As in the 7-day Cd-exposed fish, the activities of MO, AO and SO were significantly (p < 0.05) decreased in a dose-dependent manner in the gill, kidney and liver of catfish exposed for 21 days. Same is true for XO in these organs after both duration of exposure, except in the liver where no significant change was observed relative to control. The inhibition of these oxidative enzymes in the liver, gill and kidney of catfish may interfere with their biotransformation function, and ultimately the survival of the fish may be compromised.

Dose-response relationship, kinetics of formation, and persistence of S-[2-(N7-guanyl)-ethyl]glutathione-DNA adduct in livers of channel catfish (Ictalurus punctatus) exposed in vivo to ethylene dichloride

Formation of DNA adducts by reactive chemicals or their metabolites are often a precursor of mutagenesis and other adverse effects. Studies in juvenile channel catfish (Ictalurus punctatus) were conducted to determine the dose-response, kinetics of formation, and persistence of S-[2-(N7-guanyl)ethyl]glutathione hepatic-DNA adducts following a 4-h in vivo aqueous exposure to ethylene dichloride (EDC) at several dose levels. S-[2-(N7-guanyl)ethyl] glutathione adducts were detectable in liver tissue after 2 h of exposure and were still detectable three weeks after a single pulse exposure (detection limit=approximately 10 fmol, approximately 1 DNA adduct in 10(7) bases). Pretreatment of catfish with the glutathione-depleting agent diethylmaleate significantly reduced the level of tissue glutathione levels and, as a result, DNA adducts were not detected in pretreated fish. Catfish may serve as a useful sentinel species for detecting DNA-reactive chemicals in aquatic systems.

Enzymatic and histopathologic biomarkers as indicators of aquatic pollution in fishes

In the present study we investigated the alteration in the activity of two metabolic enzymes [Glucose-6-Phosphate Dehydrogenase (G6PDH) and Lactate Dehydrogenase (LDH)] and the histological changes on liver and gills of the African catfish Clarias gariepinus collected from 6 sites along the river Nile, from its spring at Aswan to its estuary at Rosetta and Damietta branches. The results showed that the physical and chemical parameters of the water collected from Damietta and Rosetta branches were higher than those of the water collected from other sites. Remarkable alterations in the activity of the selected enzymes in the liver and muscles of the African catfish were detected. These alterations go in parallel with the elevation in the levels of chemical parameters detected in the water of Damietta and Rosetta branches as a result of pollution stress in these areas. The activity of G6PDH was significantly (p < 0.05) decreased from Aswan to Rosetta and Damietta recording the highest value at Rosetta followed by Damietta water. The activity of LDH showed a significant elevation (p < 0.05) in activity in the liver and muscles of fishes collected from Rosetta and Damietta branches comparing to other sites. These alterations in enzymatic activities were followed, in the present study, by the occurrence of histological lesions and clear damage in liver and gill tissues of the African catfish collected from the same sites. Thus we may conclude that, the altered activities of G6PDH and LDH could be useful biomarkers of water pollution. At the same time, histopathology provides a reliable, easily quantifiable index of low-level toxic stress to a broad range of environmental pollutants.

Response of CYP1A Gene expression in fish liver of catfish (Ariopsis felis) from Gulf of Mexico and their relationship with the genetic variability

We determined the hepatic Cytochrome P4501A (CYP1A) mRNA and Ethoxyresorufin-O-deethylase (EROD) activities in the fish, Ariopsis felis, from highly polluted to relatively pristine regions in the southwest Gulf of Mexico and their relationship with the genetic polymorphisms of the same fish. We hypothesized that a high genetic variation reflects interindividual variability in levels of CYP1A mRNA underlying the pathway culminating in EROD induction caused by the environmental contaminants. Catfish from Laguna de Mecoacan exhibited marked induction of CYP1A mRNA and high levels of hepatic EROD activities, whereas fish from Laguna de Celestun showed no induction of CYP1A mRNA and moderately low levels of EROD activities. In contrast, the similarity index considering all samples varied from 0.4 to 0.87, showing a wide range of variation. A dendrogram showed a clear grouping of fish collected from the Laguna de Terminos, Rio Coatzacoalcos and Laguna de Celestun, with discrete subgroups according to region. In contrast, fish from Laguna de Mecoacan were grouped together completely separate from the rest of the fish. Despite the low number of fish from Mecoacan (a high bootstrap support was observed in this group), the results indicated a significant genetic variability in comparison with the other ecosystems included. The differential level of expression of CYP1A and the EROD activity observed among the ecosystems analyzed could be due to the high range of genetic variation, with special emphasis on fish collected in Mecoacan where it is possible to find a subspecies of Ariopsis felis.

Fluoride induced alterations in the arginase activity of freshwater catfish, Clarias batrachus (Linn)

Fluoride induced alterations in arginase activity in liver, muscle, kidney, gill and brain of freshwater cat fish, Clarias batrachus (Linn.) were carried out. The effect of fluoride was observed in different concentrations like 1, 10, 20 and 30 ppm in 1, 30 and 60 days of exposure. The arginase activity was found increased in all the tissues, throughout the exposure span. Maximum activity was observed on 60th day of exposure in 30 ppm of fluoride concentration. In most of the cases the elevation of arginase activity significantly differed from the controls. Gill showed maximum activity followed by liver, brain, kidney, and muscle. The increase in arginase activity indicates production of urea or ornithine.

Molecular characterization of complement factor I reveals constitutive expression in channel catfish

The complement system in vertebrates plays a crucial role in immune defense via recognition and removal of pathogens. Complement is tightly regulated by a group of both soluble and cell-associated proteins. Complement factor I is a soluble serine protease that regulates multiple pathways in complement activation. In this work, a complement factor I transcript was isolated and sequenced from channel catfish ( Ictalurus punctatus) liver after screening expressed sequence tags. The full-length cDNA is comprised of 2284 bp in length, encoding a polypeptide of 668 amino acids. The complement factor I protein was found to be well conserved, with similar domain structures and architecture from fish to mammals. The catfish complement factor I exists as a single-copied gene in the catfish genome. Expression analysis revealed that the catfish complement factor I is constitutively expressed in all tissues and leukocyte cell lines tested, indicating its importance as a regulatory enzyme throughout channel catfish. While expression of complement factor I is often found to be in the liver in mammals, it is constitutively expressed in channel catfish and carp throughout in various tissues and organs.

Cytochrome P450 induction in Ictalurus punctatus following exposure to wastewater treatment plant effluent

Induction of the cytochrome P450 enzymes in fish, measured as ethoxyresorufin-O-deethylase (EROD) activity, has been extensively used as a biomarker in assessing exposures and responses of aquatic organisms to contaminants. This study focused on whether exposure to Troy (Alabama) wastewater treatment plant (TWWTP) effluent at the Walnut Creek mixing zone, induced transcription of mRNA for cytochrome P4501A1 enzyme production and increased EROD activity in channel catfish (Ictalurus punctatus). Water from Big Creek (Barbour County, AL), regarded as least impacted by pollutants, was used as a reference source for administration of a positive control chemical (PCB – Aroclor 1254). All water samples were transported from field sites to the Troy University laboratory for conducting the study. Reverse transcriptase-polymerase chain reaction (RT-PCR) indicated the presence of compounds capable of inducing transcription of CYP1A1 mRNA in catfish liver. Increased transcription of mRNA for cytochrome P4501A1 enzyme production, confirmed by a 3-fold induction of EROD activity, was found in catfish exposed to water from the TWWTP mixing zone on Walnut Creek compared to catfish exposed to Walnut Creek Upstream. Catfish exposed to water from Big Creek treated with PCBs were found to have only slightly higher enzyme activities than those exposed to water from Big Creek Control, but a 2.7-fold EROD level was found in catfish exposed to Big Creek Control compared to Walnut Creek Upstream. Determining the induction of cytochrome P450 and subsequent enzymatic activity in catfish and other fish species common to this region could be useful early molecular warnings of possible pollution effects, beyond those methods typically used to characterize water quality.

Cloning and expression of StAR during gonadal cycle and hCG-induced oocyte maturation of air-breathing catfish, Clarias gariepinus

Complementary DNAs encoding steroidogenic acute regulatory protein (StAR) have been isolated from different fish species, yet the relevance of StAR during gonadal cycle and more importantly in final oocyte maturation has not been assessed so far. A cDNA encoding StAR was isolated from the ovarian follicles of air-breathing catfish, Clarias gariepinus. Catfish StAR exhibited 55 to 72% identity at nucleotide level with other vertebrate orthologs. RT-PCR analysis of tissue distribution pattern demonstrated the presence of StAR mRNA in various tissues including gonads, kidney, liver, brain and intestine of catfish. Real-time RT-PCR analysis revealed high expression of StAR mRNA in the pre-spawning phase of ovary while it was low in preparatory, spawning and regressed phases. In testis, maximum expression was noticed during the preparatory phase. During human chorionic gonadotropin (hCG)-induced oocyte maturation, both in vitro and in vivo, StAR mRNA levels were augmented by 2 h and then declined gradually to reach basal levels by 12 h as that of saline-treated controls. Taken together, high level of expression during hCG-induced oocyte maturation vis-à-vis in spawning suggests a role for StAR, in addition to the steroidogenic enzyme genes in final oocyte maturation.

Determination of 17-Ethynylestradiol, Carbamazepine, Diazepam, Simvastatin, and Oxybenzone in Fish Livers

A method using liquid chromatography/tandem mass spectrometry (LC/MS/MS) was developed for the determination of 17alpha-ethynylestradiol in fish liver; a second method using LC/MS was developed for the determination of carbamazepine, diazepam, simvastatin, and oxybenzone in fish liver. The fish liver samples were extracted and cleaned up by using liquid-liquid extraction and solid-phase extraction before the extracts were analyzed by LC/MS or LC/MS/MS with electrospray negative and positive ionization. Recoveries of the 5 target compounds from spiked catfish liver ranged from 72 +/- 2 to 100 +/- 3%. Limits of quantification for the 5 compounds were between 4.2 and 12.3 ng/g (wet weight). Ten turbot (Pleuronichthys verticalis) liver samples were analyzed; levels of 17alpha-ethynylestradiol, carbamazepine, simvastatin, and oxybenzone were below the detection limits. Diazepam was detected in all 10 fish liver samples at concentrations ranging from 23 to 110 ng/g (wet weight).

Influence of cell volume changes on autophagic proteolysis in the perfused liver of air‐breathing walking catfish (Clarias batrachus)

Exposure of perfused liver of walking catfish (Clarias batrachus) to hypotonicity (-80 mOsmol/L) caused swelling of liver cells as evidenced by the increase in liver mass by 11.5%, and inhibition of [(3)H]leucine release (as a measure of proteolysis) by 37% from the radiolabeled perfused liver. Whereas, exposure of perfused liver to hypertonicity (+80 mOsmol/L) caused shrinkage of liver cells as evidenced by the decrease in liver mass by 10.4%, and stimulation of [(3)H]leucine release by 24%. Infusion of amino acids such as glutamine plus glycine (2 mM each) also caused increase in liver cell volume as evidenced by the increase in liver mass by 8.9%, and inhibition of [(3)H]leucine release by 29%. Adjustment of anisotonicity of the media without changing the NaCl concentration in the media had almost similar effects on proteolysis in the perfused liver. A direct correlation of cell volume changes or hydration status of liver cells with that of proteolysis was observed in the perfused liver regardless of whether the cell volume increase/decrease was evoked by anisotonic perfusion media or by the addition of amino acids. Thus, it appears that the increase/decrease in hepatic cell volume could be one of the important modulators for adjusting the autophagic proteolysis in walking catfish probably to avoid the adverse affects of osmotically induced cell volume changes, to preserve the hepatic cell function and for proper energy supply under osmotic stress. This is the first report of cell volume-sensitive changes of autophagic proteolysis in hepatic cells of any teleosts.

Histopathological alterations in the liver of the sharptooth catfish Clarias gariepinus from polluted aquatic systems in South Africa

There is a need for sensitive bio-monitoring tools in toxicant impact assessment to indicate the effect of toxicants on fish health in polluted aquatic ecosystems. Histopathological assessment of fish tissue allows for early warning signs of disease and detection of long-term injury in cells, tissues, or organs. The aim of this study was to assess the degree of histopathological alterations in the liver of C. gariepinus from two dams in an urban nature reserve, (Gauteng, South Africa). Two dams (Dam 1 and Dam 2) were chosen for their suspected levels of toxicants. Water and sediments were sampled for metal and potential endocrine disrupting chemical analysis. A quantitative and qualitative histology-based health assessment protocol was employed to determine the adverse health effects in fish. The analysis of blood constituents, fish necropsy, calculation of condition factors, and hepatosomatic indices were employed to support the findings of the qualitative and quantitative histological assessment of liver tissue. Assessment of the liver tissue revealed marked histopathological alterations including: structural alterations (hepatic cord disarray) affecting 27% of field specimens; plasma alterations (granular degeneration 98% and fatty degeneration 25%) of hepatocytes; an increase in melanomacrophage centers (32%); hepatocyte nuclear alterations (90%); and necrosis of liver tissue (14%). The quantitative histological assessment indicated that livers of fish collected from Dam 1 were more affected than the fish livers collected from Dam 2.